The present invention relates to a starter motor electromagnetic switch and, in particular, to a switch terminal device of an exciting coil.
FIGS. 2(A) and 2(B) are respectively a front view and a side view, sectional in part, of a conventional electromagnetic switch. In these figures, reference numeral 1 designates an exciting coil wound on bobbin 2, 3 stands for a fixed iron core, 4 points out a case which forms a yoke and to which the fixed iron core 3 is fixed, and 5 represents a plunger supported on the inner periphery of the leading end portion of the case 4 in such a manner that it can be moved in the axial direction thereof. The plunger 5 is formed of a magnetic material and forms a movable iron core. 6 designates a hook the rear half section of which is inserted in the plunger 5 and also which is supported in such a manner that it can be moved in the axial direction thereof within a certain range. The hook 6 is engaged at the front end portion thereof with the upper end portion of a shift lever (not shown) and thus is able to rotate the shift lever.
Next, 7 stands for an insulating cap which is applied through a packing to the rear end of the fixed iron core 3 and connected by staking to the case 4. The insulating cap 7 is formed of a synthetic resin. 8 points out a pair of terminal bolts which are respectively extended integrally from a pair of fixed contacts (not shown) fixed within the cap 7. To one of the terminal bolts 8 is connected a terminal in a connecting line from a battery of a power supply, and to the other is connected a terminal in a connecting line to an electric motor. 9 designates a switch terminal which is formed in an L shape and is fixed to the insulating cap 7 by an eyelet 10. The exciting coil 1 has a lead conductor la which is connected to the switch terminal 9 by means of a soldering material 11. 7a is a turn-preventive projection formed in the cap 7.
A bayonet terminal of a connecting wire from a key switch of an automobile is inserted into and connected to the switch terminal 9.
Now, FIGS. 3(A) and (B) are respectively a front view and a side view, sectional in part, of another type of electromagnetic switch according to the prior art, which are different from FIGS. 2(A) and (B) only in the structure of the switch terminal thereof. In these figures, reference numeral 12 designates a switch terminal which is constructed as follows 13 stands for a support member which is formed of a conductive material and has a substantially Z shape. One side portion of the support member 13 is fixed to the insulating cap 7 by the eyelet 10 and is connected to the lead conductor 1a of the exciting coil 1 by means of the soldering material 11. 14 points out a screw terminal which includes a seat portion 14a in the central portion thereof, a threaded portion 14b in one end thereof, and a rod-shaped portion 14c in the other end thereof. The rod-shaped portion 14c of the screw terminal 14 is inserted into a hole formed in the other side portion of the support member 13 and, is connected to the hole by welding.
A terminal (for example, a pressure attached terminal) of a connecting wire from the key switch is fitted into the screw terminal 14 of the switch terminal 12 and is tightened with a nut (not shown).
In the above-mentioned conventional starter motor electromagnetic switch, in order to correspond to the kinds of terminals of connecting wires from the key switch, there are required two kinds of electromagnetic switches, that is, an electromagnetic switch including a switch terminal 9 and an electromagnetic switch including a switch terminal 12.
Also, in the switch terminal 12 having a screw terminal 14, there is not provided any means which can prevent the rotational movement of a terminal of its opponent connecting wire and, therefore, it is difficult to position the terminal in the draw-out direction thereof. Further, the turn preventive means of the support member 13 itself, to which the screw terminal 14 is fixed, is the turn-preventive projection 7a provided in the insulating cap 7 and the support member 13 is fixed only by the eyelet 10 and soldering member 11. Thus, if a great torque is applied to the screw terminal 14, then a great moment is given to the support member 13 to thereby cause the support member to turn, with the result that the turn-preventive means may be broken or damaged.